Water vehicle

ABSTRACT

A power boat with a generally mid-ship mounted motor and propeller is provided. A rudder is disposed at the rear of the boat and generally on the longitudinal center line thereof. Straightening vanes are mounted longitudinally on the underside of the hull with the rearwardmost portion thereof located generally adjacent the forwardmost portion of the rudder. The vanes extend forwardly a distance of about one-tenth the length of the entire hull. Longer protuberances on the hull extend longitudinally from a forward position near the propeller to a rearward position near the rudder. The longer protuberances lie on opposite sides of the center line of the hull. A third shorter protuberance extends rearwardly from the propeller toward the rudder and along the center line of the hull. The hull has a convex shape relative to the water line.

' [22] Filed:

Veilleux 1 May 28, 1974 WATER VEHICLE Joseph C. Veiileux, St. George, Quebec, Canada [75] Inventor:

[73] Assignee: Moto-Naute, 1nc., Quebec, Canada May 18, 1973 [21] Appl. No.: 361,620

[52] US. Cl 115/70, 114/62, 114/67 A [51] Int. Cl 8631) 35/00, B63b 1/00 [58] Field of Search ll5/6.1, 70; 114/56, 67 A, 114/67 R, 66.5 R, 62; 9/6

[57] ABSTRACT A power boat with a generally mid-ship mounted motor and propeller is provided. A rudder is disposed at the rear of the boat and generally on the longitudinal center line thereof. Straightening vanes are mounted longitudinally on the underside of the hull with the rearwardmost portion thereof located generally adjacent the forwardmost portion of the rudder. The vanes extend forwardly a distance of about onetenth the length of the entire hull. Longer protuberances on the hull extend longitudinally from a forward position near the propeller to a rearward position near the rudder. The longer protuberances lie on opposite sides of the center line of the hull. A third shorter protuberance extends rearwardly from the propeller toward the rudder and along the center line of the hull. The hull has a convex shape relative to the .water line.

18 Claims, 3 Drawing Figures WATER VEHICLE BACKGROUND OF THE INVENTION 1. Field of Use The present invention is concerned with a power boat wherein the motor for the boat is mounted forwardly in the hull and the hull is of such a size and configuration as to be used, generally, by a single passenger or only two or three passengers.

2. Description of the Prior Art Power boats designed for only one or several passengers have become of significant interest in the art. While boats of this general configuration have a very substantial and growing place in the pleasure boat arts, these boats also may be used for patrol boats by regulation enforcing agencies such as water and game commissions, lake and river patrols and the like. Such boats have distinctive advantages in that they are of generally small size, easily ported from a land location to a water launching location and easily maneuvered in relatively shallow water. However, boats of the present class present significant problems in the art, mainly because of the forwardly positioned motor and required hull designs necessary for minimizing the draft of the hull in the water. Also, while these factors provide a boat of exceptional versatility and usefulness, they contribute to considerable difficulties in controlling and maneuvering the boatat normal speeds. These difficulties are particularly accentuated at cruising speeds, and especially when relatively sharp turns are attempted. Additionally, control becomes exceedingly difficult in strong currents or strong crosswinds. Further, in view of the relatively short hull length, longitudinal stability is a particular problem and this problem is accentuated by the combination of the position of the motor and propeller relative to the rudder and the propeller caused turbulence at the rudder.

In view of these difficulties, it would be, of course, advantageous to provide a power boat, of the class defined and essentially for single or several passenger use, which significantly improves the maneuverability and stability of the vessel. It would be a further advantage to improve, especially, the longitudinal stability of the boat and to provide greater handling predictability at cruising speeds and during relatively sharp turns.

OBJECTS OF THE INVENTION Accordingly, it is an object of the invention to provide a power boat wherein the motor is mounted forwardly in the hull and the boat is designed, essentially, for single passenger use, although more than one passenger may be carried on the boat and the present specification and claims are to be so construed.

It is a further object of the invention to provide a combination of motor positioning and hull design, along with the rudder positioning, to improve the handling, maneuverability and stability characteristics of the boat. Other objects will be apparent from the following disclosure and claims.

SUMMARY A power boat with a generally forwardly mounted motor and propeller and a rearwardly disposed rudder is provided. Straightening vanes are mounted on the underside of the hull with the rearwardmost portion of the vanes being located generally near or adjacent the forwardmost portion of the rudder. The vanes extend forwardly on the hull for a distance of about onefifteenth to one-fourth the length of the hull and are disposed generally parallel to the center line of the hull. The hull has a plurality of longer protuberances which extend from a position forward of the location of the propeller to a rear position on the hull and at or near the rearwardly most part of the hull. The protuberances are disposed at the rear position of the hull between the straightening vanes. The longer protuberances straddle the centerline of the hull and are generally parallel thereto. The hull has at least one shorter protuberance which extends rearwardly from the locationof the propeller to about one-fourth to three-fourths, e.g., onehalf the distance to the forwardmost portion of the rudder, generally along the center line of the hull. The hull has a convex shape relative to the water line for limiting lateral excursions of the boat, especially when under power. The straightening vanes provide stabilization of the boat and the protuberances provide a disruptive effect on the turbulence and torque created by the propeller and streamline vortex effects of water currents.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side view of the boat of the present invention with a portion of the hull in fragmentary view;

FIG. 2 is a bottom view of the boat shown in FIG. 1 illustrating details of the hull construction;

FIG. 3 is a rear view of the boat shown in FIGS. 1 and 2, illustrating another aspect of the hull shape.

DETAILED DESCRIPTION OF THE INVENTION It is firstly noted that the present invention does not reside in the particular materials of construction of the hull, or in the particular motor being used for power purposes, but the invention resides, mainly, in the combination of the motor and propeller position and the particular hull design which cooperates with the rudder for improving stability and maneuverability of the boat. Thus, the materials of construction of the hull may be according to any of those materials known in the art. For example, the hull may be constructed of wood, such as teak, mahogany, oak and the like, or plastic such as polypropylene, epoxies, polyesters and the like, or metals such as steel, aluminum, etc. The hull may be either smooth, ribbed, overlapped, or any of the other common modes of construction, all of which are well known in the art. Additionally, the motor may be any of the well-known conventional outboard type motors, although an inboard/outboard type arrangement or similar power device may be used if desired. Accordingly, any of the well-known control devices for the motor may be used in connection with the present invention.

The propeller shaft of the motor extends vertically from the bottom of the boat and protrudes into the water a distance consistent with normal and recommended operation of the particular motor. The motor is mounted in the forward position of the boat, and in these regards, the position of the motor is quite like that normally used in connection with single-seated boats of the present nature. The motor may be mounted just rearwardly or forwardly of the mid-point of the longitudinal dimension of the hull but preferably forwardly of the longitudinal center of gravity of the hull with the motor mounted therein and accounting for an anticipated passenger load. This will complement the position of the passenger in the single-seated boat and relatively, uniformly, distribute the load of the boat along its longitudinal axis. In any event, the motor is mounted so that the vertical center line of the motor is within from one-third to three-fourths the distance from the rearwardly most part to the forwardly most part of the hull and the term mid-ship is to be so construed. As is also generally practiced in this art, the motor will be positioned approximately on the longitudinal axis of the hull. For shorter hull lengths, it can be appropriate for the motor and the controls thereof to be positioned, in regard to the position of the passenger, so that the legs of the passenger, at least in part, straddle the motor and the controls therefor. This arrangement, especially for smaller boats, will simplify the mechanical linkages necessary for control of the motor and the rudder.

In the art of mid-ship mounted motor boats intended, primarily, for single passengers, it has been a practice to so mount the motor so that the propeller can be rotated about the axis of the propeller shaft. By thus rotating the propeller, the boat may be steered much in the manner of the simple outboard motor. This kind of steering arrangement has been favored, since experience has shown that mid-ship mounted motors adversely affect steering characteristics accomplished by conventional rudders and contribute to instability in handling. However, on the other hand, the arrangement of a rotatable motor or propeller shaft has the decided disadvantage that forces are thrown on the hull of the boat which are not along the longitudinal axis of the hull. This arrangement provides for a steering of the boat by, essentially, slipping the hull of the boat in the water in a direction askew from the major direction of travel of the boat. This kind of slipping in the water renders control and maneuverability quite unpredictable, especially in rough or uncertain currents and in strong crosswinds. Further, this mode of steering, especially in rough water and at high speeds, greatly contributes to longitudinal instability of the hull. As will also be appreciated, a sideways slipping of the hull for steering,

as described above, requires that the hull be relatively smooth and flat bottomed. Any sort of longitudinal drag on the bottom of the hull would significantly contribute to steering difficulties in the foregoing type of steering arrangement. Thus, where motors are mounted mid-ship and are used in a steering device, the hulls of such single-seated boats ,are generally quite flat and free from significant protuberances.

This latter requirement, however, causes a general longitudinal instability and a lateral instability in cross currents or crosswinds or on turning. in an effort to mitigate, at least in part, the foregoing difficulties, the art has provided rudder or tiller type devices at the rear of such single-seated, mid-ship mounted motor boats. But these rudders or tillers are generally quite ineffective in steering the boat and also are unpredictable in handling characteristics due to the uncontrolled turbulence set up the the mid-ship mounted motor. Thus, the tillers or rudders have been used, mainly, as a means of compensating for the undesired characteristics of the boat being steered by rotation of the motor or the propeller shaft. However, this kind of arrangement is complicated to operate and requires an especially adept boatsman for accurate control of the boat.

Briefly stated, the present invention is based on the discovery that a single seated mid-ship mounted motor boat may be greatly improved in handling characteristics where the motor is in a fixed longitudinal and lateral configuration for normal operation, while steering and control of the boat are accomplished by means of a rudder in combination with a particular hull shape and special hull features.

in one aspect of the invention, the hull has a convex configuration with respect to the plane of the water and at normal operational speeds will produce a pontooning" effect. Thus, by providing a convex. hull with respect to the plane of the surface of the water, at operational speeds, air is forced into this convex hull and produces an air cushion or planing effect somewhat similar to a catamaran hull operation. This effect also distributes more of the load of the hull on the outer pontoon portions and produces a drag on the hull against lateral translation of the hull in the water. This, of course, greatly increases the force required to move the hull laterally in the water and, correspondingly, increases lateral stability. Additionally, the convex hull produces a tunnelling" effect for the water rapidly moved against the hull by action of the propeller. The tunnelling effect forces the vortex created by the propeller to conform to a more streamlined configuration with respect to the rudder at the rearward portion of the boat, thus mitigating to some extent the turbulence which generally renders the rudder impractical in other similar boat designs.

In another aspect of the invention, the hull provides turbulence and torque controlling protuberances formed in the bottom of the hull which extend from a location generally adjacent to the location of the propeller rearwardly to a location generally forward of the location of the rudder or even to the rearwardmost part of the hull. These protuberances straddle the longitudinal axis of the hull and, preferably, shorter protuberances (preferably only one) extend in a similar manner essentially along the center line of the hull to the rear of the propeller but terminate forward of the rudder, e.g., one-half to two-thirds the distance from the propeller to the forwardmost part of the rudder. These protuberances provide a far more efficient use of the power transmitted by the propeller and control cavitation and like aquatic disturbances which adversely affect operation of the rudder. These protuberances also cause a lateral drag against the bottom of the hull and in effect break up a portion of the vortex caused by the propeller.

In yet a further aspect of the invention, straightening vanes are provided along the outer portion of the rearward part of the hull. These straightening vanes straddle a portion of the aforementioned longer protuberances. Preferably, the straightening vanes are located, mainly, forward of the rudder and are, preferably, very slightly skewed with respect to the longitudinal axis of the hull, with the distance from the axis to the vanes decreasing from the fonvard position to the rearwardmost position of the straightening vanes, i.e., the straightening vanes are turned inwardly at their rearwardmost portion with respect to the longitudinal axis of the hull. This arrangement creates a drag along the longitudinal axis of the hull to maintain longitudinal stability. These vanes become exceedingly important for control of the boat at normal operational speeds of 10 to 25 miles per hour.

To a lesser extent, the straightening vanes positioned rearward on the boat hull will also control the effect of the vortex, but in a more important sense, the straightening vanes in combination with the convex hull, provide a drag which prevents aft instability or, stated another way, prevents the wagging of the aft portion of the boat. These vanes in effect also greatly improve the longitudinal stability of the boat, especially on turns, and straighten the track of the boat in the water.

The invention can best be understood by reference to the drawings.

Turning now to the figures in detail and considering FIG. 1 first, the boat generally designated by I has mounted mid-ship a motor 2. A housing 3 encloses a propeller shaft (not shown) which attaches in a conventional manner to a propeller 4. The motor is suitably mounted on the boat by conventional mounting plates and brackets 5 and the operation of the motor is controlled by conventional mechanical linkages 6, 7 and 8. The opening of the hull may be sealed to egress of the water by a sealing member 9, although, if desired, a conventional motor well" may be used.

The motor 2 and propeller 4 drive the boat 1 from a forward or mid-ship location as opposed to the type of boat which uses a mid-ship motor with the propeller shaft extending to the rear of the boat. It also should be noted that the motor may be the .let type with a .let impeller and the present terms of motor and "propeller" are to be so construed.

The hull 10 has a conventional windshield 11, seat backrest and cockpit enclosure 12. Normal seating equipment (not shown) is also included in the hull. For convenience, the hull may be produced in two parts with an upper part 13 and a lower part 14 sealed together by sealing member 15. This is especially convenient when the hull is constructed ofa molded plastic, such as glass reinforced polyester.

Attached to the hull in a conventional manner is rudder l6 operated by rudder shaft 17. The rudder can be operated by a conventional wheel linkage if desired, but a simple joy stick" is quite satisfactory in this connection.

Turning now to FIG. 2, which shows the bottom of the hull, it will be seen that longer protuberances and 22 straddle propeller 4 and, preferably, as shown in the drawing, extend forward of the forwardmost portion of the propeller housing 3. Thus, these protuberances straddle the entire turbulent zone created by the propeller 4 and associated housing 3 moving through the water. The protuberances are preferably tapered as indicated at 24 and 25, respectively. These protuberances extend rearwardly on the hull and preferably extend at least adjacent to the forwardmost part of rudder 16. Here again, the rearwardmost portions of the protuberances are preferably tapered as shown at 26 and 27, respectively. There is disposed a shorter protuberance 21 (or a plurality of shorter protuberances) and, more preferably, protuberance 21 is located along the longitudinal center line 23 of the hull. Similarly, protuberance 21 is tapered at each end, as shown at 28 and 29. However, protuberance 21 does not extend all the way into the rearwardmost portion of the hull and indeed preferably terminates at a point significantly forward of rudder 16.

Also disposed on the bottom of the hull are straightening vanes 30 and 31. These vanes are suitably mounted with plates 32 and 33 secured by bolts 34, or

like attaching devices. These straightening vanes are positioned at the rearward portion of the hull, but preferably terminate, in the rearwardmost projection thereof, at approximately the forwardmost portion of the rudder, although this is not critical. A portion of the straightening vanes extending rearwardly past the forwardmost portion of the rudder loses significant amounts of the effect and functions in a somewhat superfluous manner. Likewise, a portion of the straightening vane which extends in the forward direction a significant distance beyond the rearwardmost portion of protuberance 21 does not contribute, significantly, to the effect of the straightening vanes and simply creates unnecessary drag on the hull of the boat.

FIG. 3 is a rear view of the boat, and it will be seen that the convex configuration of the hull with respect to the waterline presents a somewhat tunnel configuration to turbulence produced by propeller 4. As can be appreciated by viewing FIG. 3, protuberances 20, 21 and 22 will tend to disrupt latent instability caused by the propeller turbulence and torque in a direction transverse to longitudinal axis of the boat. In other words, the lateral movement created by the propeller vortex and torque will be disrupted by protuberances 20, 21, and 22 and tend to eliminate the effects of vortex turbulence and torquing. Additionally, these protuberances will prevent cavitation under the convex pontooning hull and prevent loss of power. This latter aspect of the invention is an important feature.

In connection with the convex hull configuration, it should be noted that the preferable configuration is not necessarily that of a segment of a circle or ellipse, but in the preferred embodiment is a combination of a straightened portion 36 having an angle 9 with respect to the waterline, a corresponding and similar portion 37, and a center portion 38 which joins portions 36 and 37. Center portion 38 may be parallel to the water line, but it is preferred that center portion 38 of the hull 10 have a very slight concave configuration as shown in FIG. 3. This concave configuration simply serves to further interfere with the turbulence created by the vortex during operation of the boat. The degree of the concave configuration is indeed not critical, and, as noted above, no concave configuration is required.

As can be appreciated from FIG. 3, during operation of the boat, air scooped up at the forward portion of the boat by the bow 40 (see FIGS. 1 and 2) is forced along the longitudinal direction of the boat to produce, essentially, an air pocket underneath the hull of the boat generally in the area prescribed by straightening vanes 30 and 31 (see especially FIG. 3). The thickness of this air pocket will be narrow and indeed will be, generally, of a thickness less than the distance protuberances 20 and 22 extend into the water. Especially for certain speeds of operation, the air pocket may be essentially defined by the location of protuberances 20 and 22. This, in effect, places a greater proportion of the load carried by the hull on outer portions 41 and 42 of the hull. The combination of this loading toward outer portions 41 and 42 with the air pocket in the center portion of the hull produces a pontooning effect. Thus, in order for the hull to slide laterally in the water, for example to the right as illustrated in FIG. 3, the drag exerted by the hull at 42 must be overcome by the hull riding over the surface of the water or plowing through the water. Likewise, the drag created at section 41 must be similarly overcome. Since the convex configuration of the hull accentuates these drags, lateral translation of the boat in the water is substantially subdued except for all but the most forceful of lateral movements. This greatly increases the lateral stability of the present boat, as compared with boat constructions of the prior art.

In this latter connection, straightening vanes 30 and 31 wili additionally subdue lateral translation of the boat, but the most essential effect of these straightening vanes is to prevent longitudinal instability in the boat, especially during high powered excursions at operational speeds and during relatively sharp turns. in other words, these straightening vanes effect a more uniformly stable longitudinal tracking of the hull and prevent the aft portion of the hull from a waggle or fishtail type of instability. As can be appreciated from FIG. 3, the outward spacing of the straightening vanes, in connection with the aforementioned air pocket, will present a significant drag against lateral translation of the hull at the rearwardmost portion of the hull. However, since these straightening vanes, generally, are forward of the rudder, they will not adversely affect rudder operation.

As can also be appreciated, the angle 9 can vary substantially and the effect of this variation directly increases or decreases the resulting air pocket and drag against lateral translation of the hull as discussed above. Generally speaking, 9 can be as little as 1, although it is far preferable that 9 be at least 2 and especially at least 3. On the other hand, 9 can be as great as 18. although it is preferred that 9 be less than and especially less than about 8. Trial and error has shown that a very good angle 9 is approximately 430.

The lateral position of straightening vanes 30 and 31 are generally midway between the outermost portion of the hull bottom and the longitudinal centerline 23 of the boat, although it is preferred that the straightening vanes 30 and 31 be slightly closer to the outermost portion of the bottom of the hull than the longitudinal centerline 23, as is shown in FIG. 3. However, there is some latitude in this connection, especially with variations in angle 6. Thus, the straightening vanes can be positioned, with respect to the distance from the outermost portion of the bottom of the hull to the longitudinal center line 23 of the hull, whereby the straightening vanes are at least about two tenths the distance from the outermost portion of the bottom of the hull to the longitudinal centerline 23 of the hull, although it is preferred that the straightening vane be at least three tenths and preferably about four tenths of that distance. On the other hand, the straightening vanes 30 and 31 can be as close to the centerline of the hull as about six tenths or even sixty five one-hundredths of the aforenoted distance.

Similarly, protuberances 20 and 22 should be at least five tenths of the distance and more preferably at least six tenths of that distance, especially about sixty five one-hundredths of that distance. The protuberances 20 and 22 can be as close as about eight tenths of that distance, i.e., from the outermost portion of the bottom of the hull to the longitudinal centerline 23 of the hull. Of

course, as noted above, it is preferred that a third protuberance 21 be positioned essentially on the longitudinal center of the hull but in any event no more than three tenths of the distance from the longitudinal center line to the outermost portion of the hull.

it is preferred that the straddling protuberances 20 and 22, as described above, as well as the straddling straightening vanes 30 and 31, be in pairs and positioned, generally, from the center line equidistantly, although if desired, one of the protuberances 20 and 22, or straightening vanes 30 and 31 can be at a distance different from the distance of the other of the protuberances or straightening vanes from the centerline. However, no advantage is obtained thereby and any significant variances in the distances will adversely affect the operation of the boat.

The distance which the straightening vanes 30 and 31 extend from the bottom of the hull into the water can vary, but it is preferred that the straightening vanes extend from the bottom of the hull a distance of at least one-half inch and more preferably at least three-fourths inch, e.g., 1% inches, although, the straightening vanes may extend from the bottom of the hull considerably more than this, i.e., up to 3 or 4 inches or more. However, these greater distances that the straightening vanes extend from the bottom of the hull are not normally required and will simply produce superfluous drag. The protuberances 20, 21 and 22 may extend from the hull about the same distances as the straightening vanes, although generally the distance of the pro tuberances can be considerably shorter, bearing in mind the longer length of the protuberances. Thus, the protuberances can be from as little as three-eighths inch beyond the bottom of the hull, but this is a very minimum distance and generally at one-half inch up to about 1 inch or more is preferred.

As noted above, it is preferred that the straightening vanes be slightly askew of the centerline 23, and in this connection, the degree of the askew configuration is not narrowly critical and can vary considerably. However, it is preferred that the straightening vanes be skewed with respect to the longitudinal centerline 23 of the hull so that the forwardmost positions of the straightening vanes are slightly further apart than the rearwardmost positions. The difference in the distances which the forwardmost portions are apart, as compared with the distances that the rearwardmost portions are apart will generally be less than a 15 percent difference, especially less than a 10 percent difference and more generally speaking less than a 2 percent difference, i.e., about a 1 percent difference. For example, if the rearwardmost portions of the straightening vanes are 23 inches apart, then the forwardmost portions of the straightening vanes would be approximately 23% inches apart, the above distances being exemplary in nature and varying with the dimensions of the boat 1.

What is claimed is:

l. A motor powered boat comprising a hull, a rear mounted rudder, and a motor and propeller mounted generally mid-ship of the hull;

a plurality of straightening vanes disposed on the under surface of the hull and positioned on each side of the center line of the hull, said vanes extending longitudinally from a position on the hull near or adjacent to a forwardmost portion of the rudder to a position on the hull rearwardly of the propeller;

a plurality of longer protuberances disposed on the under surface of the hull and positioned on each side of the center line of the hull, said protuberances being disposed inwardly of said vanes and extending longitudinally from a rear position on the bull to a position on the hull at least adjacent the forwardmost position of the propeller; and

the under surface of the hull having a convex shape capable of providing an air pocket generally between the under surface of the hull and the water upon which the hull floats when the boat is moved at operational speeds.

2. The boat of claim 1, wherein at least one shorter protuberance is disposed on the under surface of the hull and generally along the center line of the hull, said shorter protuberance extending from a rear position on the hull to a position on the hull rearward of the propeller.

3. The boat of claim 2, wherein the said shorter protuberance extends less than about half the distance from the rearward position of the propeller to the rearwardmost part of the hull.

4. The boat of claim 1, wherein the protuberances have tapered ends.

5. The boat of claim 1, wherein the longer protuberances are positioned laterally of the centerline of the hull from about five tenths to about eight tenths of the distance from the outermost portion of the bottom of the bull to the longitudinal centerline of the hull.

6. The boat of claim 5, wherein the longer protuberances are positioned at least about sixty five onehundredths the said distance.

7. The boat of claim 1, wherein the straightening vanes are positioned laterally of the centerline of the hull from about three tenths to about sixty five onehundredths of the distance from the outermost portion of the bottom of the hull to the longitudinal centerline of the hull.

8. The boat of claim 7, wherein the straightening vanes are positioned about four tenths the said distance.

9. The boat of claim 1, wherein the straightening vanes extend below the surface of the hull a distance of from about three-fourths inch to about 4 inches.

10. The boat of claim 9, wherein the straightening vanes extend below the surface of the hull a distance of about 1% inches.

11. The boat of claim 1, wherein the protuberances extend below the surface of the hull from about threeeighths inch to about 1 inch.

12. The boat of claim 11, wherein the protuberances extend below the surface of the hull about one-half inch.

13. The boat of claim 1, wherein the straightening vanes are askew to the longitudinal centerline of the hull with the forward portions of the vanes further separated than the rearward portions by a difference of about 1 percent to about 15 percent.

14. The boat of claim 13, wherein the percentage of difference is about 1 to 2 percent.

15. The boat of claim 1, wherein the portion of the hull between the longer protuberances is slightly concave relative to the remaining portion of the hull surface.

16. The boat of claim 1, wherein the convex portion of the hull surface comprises two relatively plane hull surfaces extending from a lower outer edge of the hull to the two protuberances each at a selected angle 9 relative to the horizontal, 9 varying from about 1 to about 18.

17. The boat of claim 16, wherein 9 varies from about 3 to about'8.

18. The boat of claim 17, wherein B is about 430. 

1. A motor powered boat comprising a hull, a rear mounted rudder, and a motor and propeller mounted generally mid-ship of the hull; a plurality of straightening vanes disposed on the under surface of the hull and positioned on each side of the center line of the hull, said vanes extending longitudinally from a position on the hull near or adjacent to a forwardmost portion of the rudder to a position on the hull rearwardly of the propeller; a plurality of longer protuberances disposed on the under surface of the hull and positioned on each side of the center line of the hull, said protuberances being disposed inwardly of said vanes and extending longitudinally from a rear position on the hull to a position on the hull at least adjacent the forwardmost position of the propeller; and the under surface of the hull having a convex shape capable of providing an air pocket generally between the under surface of the hull and the water upon which the hull floats when the boat is moved at operational speeds.
 2. The boat of claim 1, wherein at least one shorter protuberance is disposed on the under surface of the hull and generally along the center line of the hull, said shorter protuberance extending from a rear position on the hull to a position on the hull rearward of the propeller.
 3. The boat of claim 2, wherein the said shorter protuberance extends less than about half the distance from the rearward position of the propeller to the rearwardmost part of the hull.
 4. The boat of claim 1, wherein the protuberances have tapered ends.
 5. The boat of claim 1, wherein the longer protuberances are positioned laterally of the centerline of the hull from about five tenths to about eight tenths of the distance from the outermost portion of the bottom of the hull to the longitudinal centerline of the hull.
 6. The boat of claim 5, wherein the longer protuberances are positioned at least about sixty five one-hundredths the said distance.
 7. The boat of claim 1, wherein the straightening vanes are positioned laterally of the centerline of the hull from about three tenths to about sixty five one-hundredths of the distance from the outermost portion of the bottom of the hull to the longitudinal centerline of the hull.
 8. The boat of claim 7, wherein the straightening vanes are positioned about four tenths the said distance.
 9. The boat of claim 1, wherein the straightening vanes extend below the surface of the hull a distance of from about three-fourths inch to about 4 inches.
 10. The boat of claim 9, wherein the straightening vanes extend below the surface of the hull a distance of about 1 1/4 inches.
 11. The boat of claim 1, wherein the protuberances extend below the surface of the hull from about three-eighths inch to about 1 inch.
 12. The boat of claim 11, wherein the protuberances extend below the surface of the hull about one-half inch.
 13. The boat of claim 1, wherein the straightening vanes are askew to the longitudinal centerline of the hull with the forward portions of the vanes further separated than the rearward portions by a difference of about 1 percent to about 15 percent.
 14. The boat of claim 13, wherein the percentage of difference is about 1 to 2 percent.
 15. The boat of claim 1, wherein the portion of the hull between the longer protuberances is slightly concave relative to the remaining portion of the hull surface.
 16. The boat of claim 1, wherein the convex portion of the hull surface comprises two relatively plane hull surfaces extending from a lower outer edge of the hull to the two protuberances each at a selected angle Theta relative to the horizontal, Theta varying from about 1* to about 18*.
 17. The boat of claim 16, wherein Theta varies from about 3* to about 8*.
 18. The boat of claim 17, wherein Theta is about 4*30''. 